High-frequency tube structure with frequency control



' s. F. VARIAN 2,515,280 HIGH-FREQUENCY TUBE STRUCTURE WITH FREQUENCY CONTROL Original Filed Nov. 25, 1943 July 18, 1950 INVENTOR TORNEY SIGU ,q BY f 5 I Patented July 18, 1950 UNITED STATES PATENT OFFICE HIGH-FREQUENCY TUBE STRUCTURE WITH FREQUENCY CONTROL Sigurd F. Varian, Garden City, N. Y., assignor to The Sperry Corporation, ncorporation of Delaware Original applicationNovember 25, 1943, Serial No. 511,722. Divided and this application March 2,

1945, Serial No. 580,526

6 Claims. (Cl. 315) 1942, and patented Januaryzl, 1947 as U. S. Patent No. 2,41%,496. 7

Electron discharge apparatus of the type wherein a beam of. electrons is passed in energy exchanging relation with the electromagnetic field of a hollow resonator-device are widely used,

especially in ultra highfrequency systems. In most of such systems, careful and reliable frequency control over the resonator circuit is important. It is known that the effective capacity and inductance of the circuit of a hollow resonator device depends mainly on the shape and/or volume of the resonator, and various arrangements and mechanisms have been heretofore suggested for variably controlling the circuit characteristics and frequency of the resonator by altering the resonator shape and/or volume.

The present invention contemplates improvements in such electrical and electromechanical frequency control of hollow resonator devices.

The major object of the invention is to provide novelelectrically energized, extremely sensitive, thermally responsive apparatus and methods of frequency control for hollow resonator devices.

A further object of the invention is to provide novel frequency control arrangements for a hollow resonator device wherein a thermally responsive frequency control. member such as an expansible and contractible wire operatively connected to said device is heated by electrical means.

A further object of the invention is to provide novel frequency control arrangements .for hollow resonator devices wherein-the. temperature of a thermally responsive tuning. control member is regulated by suitable electrical. energization.

It is a further object of the-invention, to pro- Aheavy radial. flange 94, rigid with drift tube vide electron discharge hollow resonator apparatusembodying a plurality of hollow resonator devices coupled by an electron beam and having novel thermally responsive gang and/or individually actuatable frequency control arrangements for such devices.

It is a further object of the invention toprovide hollow resonator means having portions relatively movable for frequency control and a non rigid thermally responsive frequency control member operatively associated with said portions.

A further object of the invention is to provide novel frequency control apparatus for a hollow resonator device embodying a spring biased nonrigid control member operatively connectedto said device. y Further objects of the invention will presently appear as the description proceeds in connection with the appended claims and the annexed drawing wherein:

Figure 1 is an elevation view, partly in section, illustrating anembodiment of the invention ineluding simultaneous and individual thermally actuated frequency control in a multiple hollow resonator device; and

Fig. 2 is an elevation view, partly in section, illustrating another embodiment of the invention wherein a flexible non-rigid frequency control member is operatively connected to a hollow resonator device.

or differential tuning.

Two hollow cylindrical resonators BI and 82 are connected by adjacent flexible walls 83 and 84 to a drift passage tube 85. Resonators 8i and 82 are preferably made of. copper, with flexible walls 83, 84 comprising annularly crimped areas having sufficient resiliency to tend to return to their illustrated positions, where the general planes of the walls 83, 84 are normal to the resonator axes. Electron permeable grid pairs 85, 81 and 88, 89 are provided on opposite ends of tube and the adjacent resonator walls. A suitable cathode 9| is mounted in alignment with the grids, and the usual concentric line terminals for supplying or extracting high frequency energy are providedat 92 and 93.

85, is disposed substantially equally intermediate similar parallel flanges 95 and 98, which are rigid with grids and 89 respectively. A plurality of circumferentially spaced adjustable screw assemblies such as indicated at 91 and 98 are provided between the associated flanges as illustrated. Usually screw assemblies 91 and 98 are so adjusted as to produce some flexure of walls 83 and 84 so as to select a predetermined grid spacing and keep the parts tight.

One pair of the screw assemblies is thermally responsive and controllably energized as illustrated at the left of Fig. 1. less steel, aluminum, Duralumin or the like, having high coeflicient of expansion, is held between flange 94 and a short screw IOI threaded in flange 95. Similarly an aluminum or like strut I02 is held between flange 94 and a short screw I03 threaded in flange 96. Heater coils I04 and I05 of resistance wire are electrically insulatingly mounted about rods 99 and I02 respectively.

A battery I08 has a voltage-dividing resistor I01 in parallel therewith and both heater coils I04, I05 are connected across the resistor I01 so that adjustment of tap I08 similarly varies the power delivered to each coil I04, I05. The lead to coil I 04 also passes through an adjustable resistor I 09 by which the relative power delivered to coils I04 and I05 may be varied for trimming or diflerentially tuning the resonators.

Usually three 120 spaced tuning control assemblies are employed, two aligned screw assemb ies 91, 98 and one aligned strut arrangement The small frequency control move- A strut 99 of stainand H8 are provided in wall II 2 and the inner end of post I I4. The outer end of post I I4 is secured to a conventional pronged vacuum tube base II1. On the other side of resonator III, a shallow cup-shaped metal reflector II8 is suitably mounted within a glass or like sealing cap H9. Reflector H8 is electrically connected by wire I20 to an external terminal I2I by which a suitable potential may be applied to the reflector. A cathode I22 extends within the post H4 in alignment with the grids and reflector.

Radial flanges I23 and I24 are provided rigid with grids H5 and H6 respectively. A plurality of circumferentially spaced adjustable length screw assemblies I25 (only one shown), each biased by associated tension sp i s are p vided between flanges I23 and I24, for manual frequency control adjustments.

Flanges I23 and I24 are formed with aligned apertures in which hollow tubes I21 and I 28 of Invar or some metal or alloy having a very low coefficient of thermal expansion are flxed and I05 and all connected to battery I00 and resistor I01 in the same manner. This will give accurate and exactly parallel relative displacement of the grids.

In operation, preliminary and rough frequency control adjustments are made with screw assemblies 91, 98 and screws WI and I03. Expansion and contraction of rods 99 and I02 by controlled energization of coils I04, I05 result in corresponding displacements of grid pairs 88, 81 and 88, 89. If the inherent resiliency of walls 83 and 84 is not suflicient to keep the parts tight, tension springs (not shown) may be provided between the flanges. Simultaneous and similar frequency control of each resonator BI and 82 can thus be obtained by adjustment of tap I08. This is electrical gang tuning. The frequency of resonator 8| may be independently varied by adjustment of resistor I09. This is a trimming adjustment to compensate for physical and/or electrical inequalities between the resonators.

I have found that, using struts 99, I02 of aluminum, an elongation is obtained of about 0.008 inch for a 300 C. rise in strut temperature. This amount of movement is ample for the usual required tuning range.

I02 may be hollow with heater coils I04, I05 inside.

This gang tuning arrangement ma be also accomplished by passing heating current directly through struts 99 and I02, the latter being suitably insulated and rigidly connected to flanges,

94, 85 and 96.

In Fig. 2, a hollow resonator III has a rigid end wall I I2 and a flexible end wall I I3 centrally supporting a hollow post II4 which extends into If desired, struts 99 and the resonator to terminate adjacent wall 2. Suitable electron permeable grid structures" H5 extend in opposite directions.

The end of tube I21 is closed by a plug I29 of insulating material in which is securely imbedded a conductive rod I3I, and the threaded outer end of rod I3I carries a reenforcing nut I32.

The outer end of tube I28 is closed by a suitable insulating plug I33 which is centrally apertured to slidingly receive a short conductive rod I34 having a threaded outer end I35 for mounting a knurled nut I36. A non-rigid expansible and contractible conductor I31, preferably a thin flexible tungsten strip or wire, is secured at opposite ends torods I3I and I34. Conductor I31 may be set at predetermined tension by adjustment of nut I36. A wire is preferable because it heats up and loses heat rapidly, thereby lending itself to automatic tuning, and a tungsten wire is preferable because of its exceptional strength and toughness even at high heat. Any metal or alloy ,therethrough may be employed for wire I31. A

suitable/compression spring I38 is arranged between flanges I23 and I24 and surrounding conductor I31.

In operation, relative separation of grids II 5 and I I0, and hence frequency control of resonator III may be effected by controllably energizing conductor I31 from an adjustable power source I39. As conductor I31 is increasingly heated, it expands in length, and spring I38 is permitted to increase the spacing between grids H5, H6 to thereby increase the resonator frequency. When conductor I 31 cools it contracts to produce the reverse frequency control. Springs I28 are not sufficiently strong to interfere with the above operation. I v

Besides permitting the use of a long wire I 31 for obtaining appreciable tuning motion, tubes I21 and I28 provide protective draft shields for in a limiting sense.

What is claimed is:

1. High frequency apparatus comprising a plurality of associated hollow resonators coupled by an electron stream; a thermally responsive expansible and contractible frequency control member for each resonator, means for simultaneously controlling the temperatures of at least two of said members, and means for independently con trolling the temperature of one of said two members.

2. High frequency apparatus comprising a cavity resonator having a pair of relatively movable elements for varying the resonant frequency thereof, resilient means connected between said elements for urging aid elements apart, thin, flexible and longitudinally thermally expansible wire means stretched between said elements and limiting the separation thereof in response to said resilient means, said wire means comprising an electrical conductor of appreciable resistivity,

and-means for connecting said wire means to a source of electric current as a current conduction path for changing the temperature thereof and hence the separation of said relatively movable elements and thereby changing the resonant frequency of said cavity resonator.

3. High frequency apparatus comprising a cavity resonator having a pair of relatively movable elements for varying the resonant frequency thereof, resilient means connected between said elements for urging said elements apart, thin, flexible and longitudinally thermally expansible wire means stretched between said elements and limiting the separation thereof in response to said resilient means, said wire means comprising an electrical conductor, and means for variably electrically energizing said wire for changing the temperature thereof and hence the separation of said relatively movable elements and thereby changing the resonant frequency of said cavity resonator.

4. High frequency apparatus comprising a cavity resonator having a pair of relatively movable elements for varying the resonant frequency thereof, resilient means connected between said elements for urging said elements apart, thin, flexible and longitudinally thermally expansible wire means stretched between said elements and opposing motion thereof in response to said resilient means, and means connected to said wire means for passing variable amounts of electric current therethrough, whereby the resultant variable extension or contraction of said wire means in response to heating thereof permits said resilient means to cause corresponding changes in the separation of said elements to vary the resonant frequency of said resonator.

5. High frequency tube structure comprising a cavity resonator having adjustable means for varying the natural frequency thereof, and tuning control means operably connected to said adjustable means comprising a thin, flexible and longitudinally thermallly expansible member coupled to said adjustable means which changes in length in response to temperature variations thereof, bias means coupled to said member for exerting tension on said member and maintaining said member substantially taut during operation, and an adjustable source of electric current connected to said member and adapted to pass adjustable amounts of current therethrough whereby the natural frequency of said resonator may be correspondingly adjusted.

6. High frequency tube structure comprising a cavity resonator having a pair of relatively movable electron-permeable grids, a source of electrons on one side of said pair of grids, a reflector electrode on the other side of said pair of grids, resilient means urging said grids in a predetermined direction, a thin, flexible and longitudinally thermally expansible conductive member connected to said grids for opposing said motion, said resilient means comprising means for tensioning said non-rigid member, and a source of adjustable current connected to pass current through said non-rigid member, whereby upon adjustment of the current passing through said member, the separation of said grids and hence the resonant frequency of said resonator may be adjusted.

SIGURD F. VARIAN.

REFERENCES CITED The following references are of record in the Number Name Date 1,658,953 Theremin Feb. 14, 1928 2,079,809 Kuhle et a1. May 11, 1937 2,311,658 Hansen et al Feb. 23, 1943 2,374,810 Fremlin May 1, 1945 2,408,817 Snow Oct. 8, 1946 2,414,785 Harrison et al Jan. 21, 1947' 2,438,132 Snow Mar. 23, 1948 

